Headlight-lens.



L. BELL.

HEADLIGHT LENS.

APPLICATIGN FILED DEC. l. i916A `Patel'fsmlSept 3, 1918.L

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Application led December 1, 19M. @arial No. 184,428.

To all whom t may concern.:

Be it known that l, Louis BELL, a citizen of the United States, residing at Newton, county of Middlesex, Commonwealth 1 of Massachusetts, have invented certainnew and useful Tmprovements in Headlight- Lenses, of which the following is a specification.

This invention relates to im rovement in headlight lenses, and partie rolved means for avoiding glare from the iieadlight of vehicles. Various diiiiculties have developed in the production of devices of thissort, and it is to the overcoming of these difficulties that my present invention relates..

The light Ished fromfthe ordinary parabolic reiector is instead of a parallel beam,

arly to ima sheaf of divergent rays owing to frequent marginal errors of the parabola and dimensions of the filament or flame.

' headlight and adapted to present invention contemplates a combine utilization of the somewhat varyin rays fromthe forward part of the reflector. Brieiy, I provide for the diffusion of the erring marginal rays, the defraction and longitudinal control of the central portion of the beam. As illustrative of my invention I have shown embodiments productive of the effects above indicated as desirable and which well illustrate the principles of my invention.

Throughout the specification and in the accompanying drawings, likeA reference characters are emcployed to indicate correspondinfr parts, an in the drawings:

Tigure 1 is a view of a lens in accordance with my invention.

Fig. 2 is a vertical sectional view of the same on the axis A B.

Fig. 3 is a section on the axis of the horizontal cylindrical curvature, and

Fig. 4L is a central vertical a lamp equipped with a lens in accordance with my invention.

My lens .consists of the usual circular disk or screen employed to form the front of the be disposed in front of` a parabolic refiector, not shown, but is formed with an annular rim or edge 1 preferably having arallel faces and of ina- .terially greater width than the frame of the front'ci the lam in which it is set. This rim 1 while it pre erably has substantially section through` parallel faces is roughened upon one or both such faces either by stipphng, ribbing or corrugating, radially, or in any other manner so as to form a diffusing surface which will be exposed within the frame of the lamp and through which the marginal rays of erratic divergence will pass as stronglydiffused light.

I have found that the common practice "of making the circumferential edge of a head-` light lens in the form of a plane annulus of clear glass either with or without a circumferential bead that it gives no securityv of locking the lens against accidental rotationdue to vibra-v tion of the car, and in fitting the lens to lamp fronts of slightly var tl`v e is risk of an annulus o nous lare.

'In t e case of rismatic .lens fronts itis equally objectlona le to carry the prisms to the extreme periphery of the front since it' becomes diflicult to secure a `dust-tight joint and the strain of the clamping device whatever it may be being borne at the apexes of the prisms. There is risk of strain and cracking of the lens. There is also, in case it is necessary to trim the lens slightly to fit risk of chipping and structure. I therefore ture of this surrounding the prismaticl redistributing portion of the lens to an extent maintaining practical uniform thickness to the'extreme periphery of the lens disk. This is stippled or otherwise roughened so that it both dispersos the light and furnishes a surface so roughencd as'to hold the lens against turningfrom vibration.

Within this annular on the interior face o a front, considerable damaging the prism provide in the strucportion 1 I provide my lens top and lng diameters clear glas's being exposed, from which there may be se-v` down the diameter of invention a diffusing annulus' ety is practically objectionable in ttom prlismatic elements preferably develi opedfas a cylindrical convexity of horizontal axis C D and lshaped to secure the control] and predetermined vertical dispersion of the f, p rays of the light transmitted within the diffusing annulus 1. On the cxtrior surfaceof the lens, l form a laterally diver 'ng element preferably being a cylindrical concavity in this instance of vertical axis A l5 This 1s so shaped as to secure the control and predetermined lateral dispersion of the iet ' down below t rays within the diffusing annulus. These axes A B and C D of the inner and outer cylindrical curved surface cross each other at right angles but not necessarily at the center of the lens as hereafter set forth.

It may further be pointed out at this time that the planes in which these axes lie may be in substantial ,parallelism or at an angle to each other. Furthermore of these two faces, either may be ahead or instead of being on opposite sides of the lens they may be merged into a single face of compound curvature. One or both surfaces may be developed in the Fresnel form. Referring to Fig. 1 it will be noted that the e lindrical curvature of horizontal axis is in icated as preferably intersecting the Vertical axis of the cylindrical curvature of the outer face below center. This effects a better distribution of the divergent rays in the upper ortion of the li ht beam so as to brin 't em ge `horizontal while stil redistributing to somewhat lesser extent any divergent rays produced in the lower part of the reflector and which are intercepted by the roadway more adjacent to the ear, thus lifting them toward the horizontal. In the same manner the vertical axis of the exterior cylindrical curvature may be decentered so as toproduce better convergence and overlapping of roadway intercept of rays from a pair of lamps. The annular dispensing area 1 in the margin of the lens 2 is preferably carried from the extreme periphery of the lens to a sufficient distance so that it will be exposed well within the marginal overlapping of the frame of any lamp front.

xThe stippling or other roughening of this diffusing annulus se as to ailord a considerable margin is not only of advantage on acs count of its function in taking care of the marginal errors of diil'erentpa'rabolas, but it being uniform `clear to the periphery makes of this area an element which may be trimnledvdown to t a lamp of peculiar diameter lwithout inconvenience. The two faces of this annulus are therefore preferably parallel faces althoughthere may be slight divergence. The stippling or other roughening of `this annulus to the periphery is furthermorev of mechanical advantage as a means of preventing thcaccidental turning of the lens and the loss offadjustment ofiits axes under the vibration of the roadffor by careless handlingl:

Various modifications in ythe form `and construction of my invention may obviously be resorted to if within the limite of the appended claims.

What I therefore claim and desire to secure by Letters Patent is:

1. In combination, a headlight having a lens clamping front, a lens having refracting elements disposed to deflect thebeam downward in the vertical plane and laterall in the horizontal plane and a roughen margin entirely about the edge thereof and extending to within the grasp of said clamping front. o 1

2. A headlight lens having a central light transmitting area formed with cylindrical surfaces of crossed axes of opposite sign for regulating the distribution of light passing through such area, Vand a marginal roughened area. I

3. A headlight lens formed with cylindrical surfaces developed from crossed axes. of opposite sign and a marginal diffusing area reaching the periphery of the lens.

4. In combinat1on with a headli ht having a reflector for substantially para el rays, a. lens having a central light transmittin area formed wlth refractive surfaces cyhndrically developed from crossed axes and of radii of op osite sign.

5. In com inationwith a headli ht having a reflector for substantially para el lays, a-

lens having a central light transmittinurea formed with refractive 'surfaces cy dtieally developed from crossed deeentered 'axes and of radii of opposite si eef 6. In combination with'a leadlighthavilig l a reflector for substantially parallel rayei` a lens formed with refractive surfaces cyll'llo drically developed from vertically and hurl.

zontally crossed axes and of radii of oppio site sign. 1 y, 7. In combination with a headli ht having a reflector for substantially aral el rays, a

lens formed on its opposite aces with sur faces. of cylindrical curvature of opposite sign, the axes of cylindricityheing crossed' at l substantially right angles. a y

8. A headlightlens having light uting surface formed with concave and'ccn.q

iet

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vex cylindricity' developed on suntially vertical and horizontal axes respectively.v

In testimony whereof I aflix` my signature' in presence of two witnesses.

. LLUIS Witnesses 

